MOSCOW, June 30. / TASS/. Russian Foreign Minister Sergey Lavrov is due to meet in Vienna on Tuesday with his German and Iranian counterparts Frank-Walter Steinmeier and Mohammad Javad Zarif, a source in the Russian delegation told TASS.

"Sergey Lavrov is due to hold a number of bilateral meetings, including with his German and Iranian counterparts," the source said.

Also on Tuesday, Lavrov will hold talks with US Secretary of State John Kerry.